It's not actually stuck. I'm guessing the 57% mark is when the biggest archive is being patched. The length of the whole process depends on how much free space you have (the installer needs to copy tens of gigabytes) and whether you're using hdd or ssd. I had a lot of free space left and the whole process took around 15-20 min (on a ssd).
Also you can't mix offline 1.04 patch with Galaxy version.
Richi_Bowzer: just pause it up the top and restart, my thing was my drive had 53gb left and said not enough room for 500 odd mb patch lol, it seems the patching system is thinking you need the games full 59gb space to apply the 500 odd mb patch lol... not a cdproject red issue as I suspected it was this, moved some stuff to make 59 free and it started the 500 odd mb patch lol
The patching system is right:
https://twitter.com/GOGcom/status/1337505298156834817